Gain And Phase Calibration In Array Channels And Its Implementation

Direction of Arrival (DOA) estimation and beamforming are two important areas of array signal processing with widespread applications in engineering, such as radar, sonar, communication, biomedicine, etc. A number of high-resolution DOA estimation algorithms and digital beamforming methods are based on the assumption that array errors do not exist. Array errors, which include channel gain and phase error, sensor position error and mutual coupling, are universal in practice. So this thesis aims at the gain and phase calibration in array channels and its implementation.First, based on the established array signal model, the theories of high-resolution Multiple Signal Classification (MUSIC) and linearly constrained minimum variance (LCMV) adaptive digital beamforming method are elaborated. Then the array signal channel gain and phase error model is presented, and the influence of the channel gain and phase error on the MUSIC algorithm and the LCMV adaptive beamforming method is also analyzed. Subsequently, two methods of channel gain and phase error calibration: gain and phase calibration for narrow-band system and channel equalization are introduced. In this thesis, two channel equalization algorithms, named time-domain based algorithm and frequency-domain based algorithm, are mainly investigated. Besides, the impact of some parameters on equalization performance is discussed in detail. Finally, the flowchart of gain and phase calibration system in a project is presented. Moreover, the compilation of program in FPGA chip and the flow of algorithm in DSP chip are illuminated. The comparison of the results from a simulation with that from a hardware platform shows the effectiveness and feasibility of the calibration algorithm.